Thermostat.



G. E. SPEAR.

THERMOSTAT.

APPLICATION FILED mm2?. m5.

1 ,258, 1 6 1 g Patented Mar. 5, 191&

QQ 1520 J/ s O L UNTTED STATES PATENT OFFTCE.

11.' :;sxr i 1: j i i .e :GEQBGAEJa or Bestron, MLAssAcHUsETTs, Assrenpn To ,STANDARD THERMOM- ETEB coMPANY, oF PORTLAND, MAINE, A CORPORATION or MAINE.

THERMOSTAT.

Specification of Letters Patent.

ratented Mar. 5, 191s.

VApplication tiled March 27, 1915. I Serial No. 17,398.

lscription ofthe invention, such as will en- I'able othersY skilled in the art to which it appertain's tomakeand use the same.

Theapr'esent :invention relates to improve- .-n'ientsin thermostats,;and more, particularly *eally egulatixig heating apparatus. The obl'jects of the invention f areztosecure. greater eiiiciency nanda ,more compact device by means Vof a; novel -re arrangement of the -parte' eo'mposi ,ithermostatic apparatus,

and to the'ere sathednventio'n eonsistsm the Athermostat' hereinafter described and particularly 'defined inthe .-claims.

In-the,drawings :accompanyin 4@this :ap-

i licatie'n and illustratngthepre erred emodimnt of the iavention,.-Figure 1 is aplan of the improved thermostat'with .aportion inse'ction showing-the thermostatic expansible member; Fig; 2 is Sase'ctional view. `on line 2 2 of 1; Eig..3 is a-s'ectional view on line 3-43 o Eig. l; and iFig. 4 is a sectional view on line 4:-4 of Fig. 1.

The .thermstatic apparatusis mounted in afname consisting `of an upper portion or casing 5 in `which =is' inclosed the indicating mechanism and -a baseer standard 6, projecting'lrfrmthe lower end ,ofwhiehis a tube' .'for supportingthe e'xpansibl'e member B which is incased in an expansion chamber 9 ,formed by a cap 10 which fits intothe hase of the standard. The standard is provided with a threaded portionll so thatthe; thermostat, may be screwed into the Ito ofra boiler or other heating apparatus, Awith ,the chamber projecting into the interioriof the same. The active or expansible membenis spiral in form, and is se- ,cured vat 'its loweinend 'to the tube The up- Vperendis connected bythe arm -12 to the rod 13 which extends upwardly through a longituduahope'ningrin the standard. The redis suitably supported at mand 15, and ,uponvits ,upper end is adjustably mounted a radial contact piece or circuit closer 16. ,When the active member is expanded or fcont-racted, according to the temperature,

the contact piece is caused to describe an are, Atherebyclosir'ig or opening either one of twoelectric circuits. The heat responsive `parts just described are, or may be.l of any usual orpreferred construction.

,The indicatlng mechanism, which con1 prisesa pointer and its. controlling devices and associated parts, is mounted upon a dial plate 419. Adjustable contact member .sup

:portsfor u rights A2Oand 21, are insulated from the dlal and from the casing by. means .of washers of mica 23 or in any other suit ,able manner. The.dial plateissupported within the=casing and rests upon ashoulder .24 therein-,being held inpositionzby a strip of metal 25 upon which rests a lass plate 26 tojpermt inspection of ,the dif aflange on rim 27,which tsztightly around, the up- ;:ofQtheppei-iphery-:of the face of the .casingns provided witha'r lip 28 which holds theiglass in place. Themovements of the Apointer ofthe indicating mechanism and of .the :adjustable contact members are. controlled .by a .hard rubber knob 29, fastened tothezouter end'ofa .threaded movement rod or regulating screw 30 which is mounted in lock-beseuings,Y 31: and32 secured to the dial plate; the collar 33, when properlvl adjusted, prevents -endwise motion of. the rod. The pointer 34 is secured to a ,segmental worm 35 .vvhich.is engagedA by the larger of thetwo threaded portions of the movement rod. ,The

vsmaller of the threaded portions engages au vupright ena reciprocable contact membei` carrying plate 36, two laterally projecting farms of-which support the contact uprights 20 and '21 which carry the adiustable contact members or scre'ws 37 andy 38. The contactplate is mounted slidingly on the dia! ,plate and is held against detachment there- .from by a washer lwhich is held in engagement with the dial plate by a screw 4l which travels laterally-,1n a slot `42 in the diaLplate. The casing isprovided with binding posts 43, 44, and so that the casingmay be connected in two electrical circuits, one wireof onecircuit beingattached to the post 43 which is connected by a `Wire with the contact uprghtf20, -andone wire of the other circuit being attached to the postV 45 which Lislconnected hva Wire to the contact upright 21. i n A .wire..common to both ,circuits is `attachedto the binding 44which .is .not insulated from `the casing. Posts 4B vand t5 are insulated from the casing by means of bushings 46 made of hard rubber or -other insulating material. The above described electric arrangement is such that when the expansion member is caused to expand by the heat, the radial contact piece or circuit closer 16 makesra contact with one of the contact screws and through the casing closes one circuit, thereby operating in one direction the dampers or other devices to which the regulator is connected by any suitable means. When the expansionmember is caused to contract by'a drop in the temperature. the radial vcontact piece makes a contact with the other of the contact screws and through thecasing closes the other circuit. thereby operating the dampers or other devices in the opposite direction.

In thermostatsas hitherto constructed. it has been customar to house the indicating mechanism at a istance from the active thermostatic members, making it necessary to employ intermediary means in adjusting the thermostat to close the circuit at any predetermined degree 'of temperature. In the present invention. :by connecting the indicating pointer and the adjustable contacts with the regulating screw,`it is possible to hoiisethem both within the casing which has heretofore contained only either the indicating mechanism or the contacts of the thermostat. with the result that an instrument is secured in which the arrangement of the apparatus `is morefcorripact. Fewer parts are used, with the consequent result that, inasmuch as the instrument is less lia-ble to get out/of order, greaterefficievicy is assured.

i The operation of the improved thermostat is as follows: The pointer 34 is set at 150 on the dial. supposing for the sake of illustration that that is the critical temperature of the heating afrency in the heating apparatus. The contact plate 36 will now be ft about tlie middle of its movement course; the adiustable contact screws 37 and 38 are set at an eqial distance from each side of the circuit closing piece 16 which is arranged vertically. The graduations on the dial plate are spaced to correspond to the variations in temperature to which the thcrmostat is subiected. as they would he indicated on a thermometer. If the heating agency is to be vmaintained at substantially 150 degrees. the contact screws will be so adjusted in relation to the piece 16 that a slight variation in temperature will serve to cause the piece l16 to be moved either to the left or right and thereby-set in operation the apparatus by which the dampers' or other devices are controlled to raise or lower the temperature of lthe heating medium as required. If now it is desired to maintain the heating agency at 200 degrees the knob 29 is turned until the pointer reg- 'when the temperature has reached the predetermined 200 degrees the member 16 will contact with the screw 38, thereby closing its circuit and operating the damp'ers or other Aheating regulating means by the usual media.'

The turning of the regulating screw 30 which effected a change in the indication of the pointer and a shifting ofl the contact plate 36 from a central to a fright handposi- 'i tion. did not affect the distance between the contact screws 37 and 38, so the same slight variation in temperature will cause an operation of the heat regulating media as when the temperature of heating agency was to be maintained-at 150 degrees. A greater or less variation in temperature from the desired point. mav be secured bv adiiistinar the contact screws in relation to Vthe circuit closing piece. From the foregoing description it is apparent that whenthe thermostat is once vSet for anv griven'temncratiire. a change of temperature mary be securedV simply. by'indi- 'catnfr the desired temperature. f

Having now described my improved thermostat. what T claim is:-

1. An indicatiner mechanism for thermostats having. in 'combination with a circuit closinqr piece. a recinrocatorv contactplate, contact supports mounted4 thereon. adiiist able contact screw; invthe supports. a pivot- .ed n'ointerprovided with teeth. and a remilating scrcw lvinsr in siibstantiallv the same plane with the pointer and harina' two threaded portions, onf` of which is in engetfement with the pointer. and the other of which is in engagement with the plate for movinfr the pointer and the contact screws synchronoiislv.

2. An indicating mechanism For thermostats having. in combination with a circuit closing piccina dial. a pointer pivotcd thereon provided with teeth. a contact plate. contact members carried bv the plate. and a remilatine screw lvinrr siihstantiallvfin the same plane with the lpointer. in Yensl'agemcnt with the pointer tee+h and'with the contact plate. for moving the pointer relatively to the dial and svnclirononslvtherewith the contact members respectively toward and from the circuit closing piece.

3. An indicating mechanism For thermostats having, in combination with a circuit closing piece, a dial, a pointer pivoted thereon provided with teeth, a contact plate, contact members carried by the plate, and a regulating screw having two threaded portions, one of said threaded portions engaging the pointer teeth so that the pointer may be moved relatively t0 the dial, and the other ot' seid threaded portions engaging the contact plate so that the contact members may be moved toward and from the circuit closing piece.

4. An indicating mechanism for thermostats having, in combination with a circuit closing piece, a dial, a pointer pivoted on the dial and provided with teeth, a reciprocatory contact plate mounted on the dial, contact members carried by the plate, and a regulating screw having two threaded portions, one of which is 1n engagement with the pointer teeth and the other of which is in engagement With the Contact plate, for imparting a pivotal movement to the pointer, and synchronously therewith a reciproca` tory movement to the contact plate.

5. An indicating mechanism for thermostats having, in combination with a circuit closing piece, a dial, a pointer pivoted thereon provided with teeth, a Contact plate carrying contact members movable toward and from the circuit closing piece, and a regulating screw lying substantially in the plane of the pointer in engagement With the pointer and With the Contact plate.

GEORGE E. SPEAR.

Witnesses:

KATHERINE J. DOOLEY, FRED H. LANGILLE.

Copies ot this patent may be obtained for iive cents each, by addressing the Commissioner of Patenti, Washington, IJ. C. 

